The diesel generators are usually used for supplying the electrical demand of the semi-submersible oil drilling rigs. The specific fuel consumption (SFC) of each diesel engine changes nonlinearly with respect to its power product. Hence, this paper presents an economic fuel dispatch model for diesel engines powered oil rig platforms using the cubic spline interpolation curve fitting of the SFC-power non-linear dependence. Moreover, the total fuel consumption of the diesel generators significantly reduces by shifting a partial part of the electricity demand of the offshore drilling rigs from on-peak time intervals to off-peak periods. In addition, battery energy storage contributes to the load curve smoothing strategy. A mixed-integer non-linear programming problem is developed under generalized algebraic mathematical modeling system to find the optimum fuel consumption and power generation schedules of the diesel producers, the value of demand increase/decrease, and the charge/discharge pattern of the battery at each operating time interval. A benchmark oil rig with eight diesel engines and four tidal turbines is considered to validate the proposed methodology. Four cases are studied without and with application of battery and load shifting program. It is found that implementation of peak-clipping and valley filling to energy demand pattern and battery integration with tidal-diesel driven oil rigs cause a significant fuel saving. In the presence of battery, 70 g fuel saving is achieved over a 24-hours study horizon. Moreover, the implementation of time-based load shifting program with the capability of 30% load decreasing (at peak hours) and increasing (at off-peak periods) makes it possible to save 282 g diesel fuel according to the base electrical demand profile. Finally, simultaneous integration of battery and demand-side management programs (with maximum 10% load flexibility) causes 216 g fuel saving in sample operation day.